The present invention relates to a method of producing a ceramic body having a construction such that cells are plugged alternately at both end faces of a ceramic honeycomb structural body.
Up to now, in order to produce a ceramic body in which cells are plugged alternately at both end faces of a ceramic honeycomb structural body, various producing methods have been known. FIGS. 15a-15c are schematic views respectively explaining one embodiment of a method of producing such a known ceramic body. According to FIGS. 15a-15c, one embodiment of the known method of producing the ceramic body will be explained. At first, as shown in FIG. 15a, a mask 54 made of rubber having holes 53 corresponding to cells 52 to be plugged at an end face of a ceramic honeycomb formed body 51 (ceramic honeycomb structural body before sintering) is prepared, and the thus prepared mask 54 is set at a predetermined position on the end face of the ceramic honeycomb formed body 51 by hand.
Then, as shown in FIG. 15b, the end face of the ceramic honeycomb formed body 51, to which thee mask 54 is set, is immersed in a plugging slurry 55, and, a pressure is applied to the ceramic honeycomb formed body 51 from above, so that the cells 52 are filled with the slurry 55 through the holes 53 of the mask 54. At the other end face of the ceramic honeycomb formed body 51, predetermined cells 52 are filled with the slurry 55 in the same manner. In this case, a mask having a reverse hole pattern such that holes are arranged at portions where no holes 53 of the mask 54 are arranged is used so as to obtain a construction such that the cells 52 are plugged alternately at both end faces of the ceramic honeycomb structural body. According to the processes mentioned above, as shown in FIG. 15c by cross section, it is possible to obtain the ceramic honeycomb formed body 51 having a construction such that the cells 2 are plugged alternately at its both end faces.
However, in the method of producing the known ceramic body mentioned above, it is difficult to make the mask 54 having the predetermined holes 53 and to set the mask 54 accurately on the end face of the ceramic honeycomb formed body 51. Particularly, in a large size ceramic body having a diameter of about 300 mm which is recently required, the number of cells 52 at the end face reaches to few ten-thousands, and thus the difficulties mentioned above become worse. Moreover, since the mask 54 is set on the end face of the ceramic honeycomb formed body 51 by hand, it is necessary for a worker to get skillful and this setting operation requires much time. In addition, there is a problem such that this setting operation is not automated. Further, after the plugging operation, it is necessary to perform a cleaning operation of the mask 54 for recycling. However, since the mask 54 has a large number of cells as mentioned above, there is a problem such that it is very difficult to clean up the mask 54.
An object of the invention is to eliminate the drawbacks mentioned above and to provide a method of producing a ceramic body which can easily plug cells at an end face and which can be easily automated.
According to a method of producing a ceramic body according to the invention, a method of producing a ceramic body having a construction such that cells are plugged alternately at both end faces of a ceramic honeycomb structural body by filling a plugging slurry into predetermined cells at both end faces of a ceramic honeycomb formed body, comprises the steps of: filling a plugging material for mask into the cells to be opened at one end face of the ceramic honeycomb formed body; immersing the end face, to which the plugging material for mask is filled, into a plugging slurry; and drying and sintering the ceramic honeycomb formed body while the plugging material for mask is removed during a drying step or a sintering step.
In the present invention, since a plugging operation of the end face of the ceramic honeycomb structural body is performed by using a plugging material for mask which can be removed at the sintering without using a mask, it is possible to eliminate a production of the mask and a setting operation of the mask with respect to the end face of the ceramic honeycomb structural body. Moreover, since a filling operation of various plugging materials for mask mentioned below can be easily automated, the plugging operation of the ceramic body according to the invention can be also automated.
As a preferred embodiment of the invention, the plugging material for mask filling step further comprises the steps of: preparing a suction jig having a same honeycomb construction as that of the ceramic honeycomb formed body; adhering a mask, in which holes are arranged corresponding to the cells to be plugged, to one end face of the suction jig; sucking paraffin balls, a diameter of which is larger than a length of one side of the cell, to the predetermined cells at the other end face by sucking from the end face to which the mask is adhered; setting the suction jig, to which paraffin balls are sucked, to the end face of the ceramic honeycomb formed body to which the plugging material is to be filled; aligning the paraffin balls to the cells to be opened by stopping the sucking operation; inserting the thus aligned paraffin balls into the cells by applying pressure; and filling the paraffin balls into the cells to be opened as the plugging material for mask. Moreover, the plugging material for mask filling step further comprises the steps of: making a mask for respective ceramic honeycomb formed bodies by piercing a sheet adhered to one end face of the ceramic honeycomb formed body at positions corresponding to the cells to be plugged; immersing the one end face to which the mask is adhered into a liquid paraffin; inserting the liquid paraffin into the cells through the holes of the mask by applying a pressure; and filling the liquid paraffin into the cells to be opened as the plugging material for mask. Further, the plugging material for mask filling step further comprises the steps of: immersing one end face of the ceramic honeycomb formed body into a photo-curing resin before hardening; emanating a light to the photo-curing resin from the other end face through a mask, in which a light is transmitted only to the cells to be opened, so as to harden the photo-curing resin; and filling the photo-curing resin into the cells to be opened as the plugging material for mask. In all the preferred embodiments mentioned above, it is possible to perform a filling operation of the plugging material for mask with respect to the ceramic honeycomb structural body effectively, and thus it is preferred.